It is well known in the art to form fibers from molten materials, e.g., inorganics such as glass, slag, refractory compositions, etc., by centrifugally spinning as evidenced by U.S. Pat. Nos. 3,326,650, 3,187,194, and 3,801,243. When such processes are used to form continuous mats or blankets of non-woven fibers, a collection problem exists. The width of the mat or blanket desired is usually much wider than the veil or column of air entrained fibers created by the centrifugal spinning. In addition to merely spreading the veil of fibers to cover the entire width of the moving collection belt, it must be done in such a manner that the layer of fibers collected is relatively uniform in thickness and density. Although many techniques have been proposed to accomplish this objective, most either fall short or present other problems or requirements that are undesirable.
One attempt to disburse the spun fibers evenly over the collection surface involves placing a plurality of fiberizing spinners in a single collection chamber, either in line or staggered, and creating sufficient turbulence within the chamber to produce a uniform cloud of fibers directed towards the collection belt. While this technique produces a mat of acceptable uniformity of thickness and density, many of the fibers in the collected mat are oriented along the thickness dimension of the mat which is detrimental to the thermal insulating potential of a fibrous mat.
Other proposals have involved oscillating a veil or column of gas entrained spun fibers back and forth in a plane running transverse to the direction of movement of the collecting surface. Early proposals involved causing the column to oscillate by manipulating a pluarality of gas jets mounted in the side walls of the collection chamber, as evidenced by U.S. Pat. Nos. 2,863,493 and 3,030,659. The disadvantages of this technique are outlined in U.S. Pat. No. 3,134,145 (column 1, lines 65-72 and column 2, lines 1-15).
Another technique is described in U.S. Pat. Nos. 3,134,145, 3,546,898, 3,625,667, and 3,877,911. This technique involves suspending an elongated hollow member below the spinner so that the veil of spun fibers is directed into one end of the hollow member. The member is then oscillated back and forth around an axis running through the top portion of the member which deflects the column or veil of fibers and directs the veil to different portions of the collection surface. Such a system prevents adding binder to the fibers until after the fibers exit the oscillating hollow member. If binder is added prior to entering the oscillating member, the tackiness imparted to the fibers by the binder would cause a buildup of fibers and binder on the interior of the hollow member and would necessitate frequently interrupting the operation to clean out the hollow member.